#region License
/*  Pvax.Utils
    Copyright (c) 2006, Alexey A. Popov
    All rights reserved.

    Redistribution and use in source and binary forms, with or without modification, are
    permitted provided that the following conditions are met:

    - Redistributions of source code must retain the above copyright notice, this list
      of conditions and the following disclaimer.

    - Redistributions in binary form must reproduce the above copyright notice, this list
      of conditions and the following disclaimer in the documentation and/or other materials
      provided with the distribution.

    - Neither the name of the Alexey A. Popov nor the names of its contributors may be used to
      endorse or promote products derived from this software without specific prior written
      permission.

    THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS *AS IS* AND ANY EXPRESS
    OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY
    AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
    CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
    DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
    DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER
    IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
    OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#endregion

using System;
using System.Diagnostics;
using System.Threading;

namespace Pvax.Utils
{
	/// <summary>
	/// Provides an abstract base class for non-poolable implementations of
	/// <see cref="IAsyncResult"/> interface.
	/// </summary>
	public class AsyncResult: IDisposable, IAsyncResult
	{
		AsyncCallback callback;

		object state;

		ManualResetEvent waitHandle;

		/// <summary>
		/// Initializes a new instance of the <see cref="AsyncResult"/>
		/// with provided <paramref name="callback"/>, <paramref name="state"/>.
		/// </summary>
		/// <param name="callback">The callback delegate to be called when
		/// the asynchronous operation is completed.</param>
		/// <param name="state"></param>
		public AsyncResult(AsyncCallback callback, object state)
		{
			this.callback = callback;
			this.state = state;
			this.waitHandle = new ManualResetEvent(false);
		}

		/// <summary>
		/// Finilizes the asynchronous operation.
		/// </summary>
		public void Complete()
		{
			try
			{
				waitHandle.Set();
				if(null != callback)
					callback(this);
			}
			catch
			{}
		}

		/// <summary>
		/// Releases the resources acquired by the
		/// <see cref="AsyncResult"/>.
		/// </summary>
		public void Dispose()
		{
			if(null != waitHandle)
			{
				waitHandle.Close();
				waitHandle = null;
				state = null;
				callback = null;
			}
		}

		/// <summary>
		/// Validates the <see cref="AsyncResult"/>.
		/// </summary>
		/// <exception cref="InvalidOperationException">
		/// The object is invalid state.
		/// </exception>
		public void Validate()
		{
			if(null == waitHandle)
				throw new InvalidOperationException();
		}

		/// <summary>
		/// Gets a user-defined object that qualifies or contains information
		/// about the asynchronous operation.
		/// </summary>
		public object AsyncState
		{
			get
			{
				return state;
			}
		}

		/// <summary>
		/// Gets the <see cref="ManualResetEvent"/> that is used to wait for
		/// an asynchronous operation to complete.
		/// </summary>
		public ManualResetEvent AsyncWaitHandle
		{
			get
			{
				return waitHandle;
			}
		}

		/// <summary>
		/// Gets the <see cref="WaitHandle"/> that is used to wait for the
		/// asynchronous operation to complete.
		/// </summary>
		WaitHandle IAsyncResult.AsyncWaitHandle
		{
			get
			{
				return this.AsyncWaitHandle;
			}
		}

		/// <summary>
		/// Gets an indication of whether the asynchronous operation completed
		/// synchronously.
		/// </summary>
		public bool CompletedSynchronously
		{
			get
			{
				return false;
			}
		}

		/// <summary>
		/// Gets an indication whether the asynchronous operation has completed.
		/// </summary>
		public bool IsCompleted
		{
			get
			{
				return waitHandle.WaitOne(0, false);
			}
		}
	}
}
